Use caution when aerating older ponds.
Be very careful if you must aerate an older pond having deep sediment which has become anaerobic. You can tell if you have a dangerous condition by stirring up the bottom sediment and smelling the rising bubbles for a very distinct sulfur smell. This smell is actually hydrogen sulfide -- or sometimes methane -- both products of anaerobic bacteria. These gases are deadly to fish and people, so be careful.
How to aerate
Whether the pond is shallow or deep, attach the foot valve to the air stone, and attach the air line to the foot valve. Put the air stone (an aeration stone, a fine-bubble diffuser) in a plastic five-gallon bucket. Connect the air line to the bucket handle with a wire tie. Make sure the air stone stays at the bottom of the bucket -- this is important.
By using a float, like empty plastic water jugs, lower the bucket and air stone only to a depth where you get no sulfur smell. Below this point if the bubbles smell of strong sulfur odor, raise the stone until the bubbles smell okay. You now know that the water below this point is saturated with hydrogen sulfide and other poisonous gases. There are no fish down there as there is virtually no oxygen in that low water.
If you lower the air stone too far and bring up too much poisonous gas too quickly, the fish will die.
The air stone will aerate the water to the sides and above it. The rising bubbles will carry a certain amount of hydrogen sulfide gas to the surface but not enough to harm the fish who are all living in the top water. Very gradually (over weeks)you can lower the air diffuser stone and bucket one foot at a time and it will clean all the water around it. Be sure to check the smell of the bubbles. If you get into strong smelly water, pull the bucket and air stone up a bit.
Eventually the stone and bucket will rest on the bottom. The rising bubbles will pull up the water from the bottom but not the sediment. This is prevented by the bucket. The anaerobic sediment is laced with bacteria-producing poisonous gases, The anaerobic bacteria cannot live in an oxygen-filled environment so the anaerobic bacteria closest to the surface of the sediment will die and be eaten by the aerobic bacteria which have been happily growing in the oxygen-rich aerated water.
Aerobic bacteria are the good guys. They breathe oxygen and exhale [CO.sub.2] just like us. They have a tremendous appetite and eat anything organic very quickly. The aerobic bacteria will continue to eat the organic sediment at the bottom of the pond as long as they are given oxygen. They also eat the dead anaerobic bacteria thereby eventually eliminating all of the anaerobic bacteria in the pond and making the water fresh from top to bottom.
For more information on pond aerators, contact John Longenecker, PO Box 5155, Beverly Hills, CA 90210; ph (800) 470-4602; www.MalibuWater.com.
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|Publication:||Countryside & Small Stock Journal|
|Date:||Jan 1, 2001|
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